Compare · Ingredients

Cysteamine vs Kojic Acid

Cysteamine: Can reduce melasma pigmentation in tested topical formulas. Kojic Acid: May help uneven pigmentation, often as part of a combination treatment.

Research updated 2026-10-25

Four cysteamine products: a Senté tube, an Omic+ cream and box, a 5% cysteamine serum dropper and a Cyspera bottle

Five kojic acid products on white, including a turmeric serum, Medicube capsule cream, Admire My Skin and Seoul Ceuticals

Which one?At a glance What it helps Diagrams Using both Strengths Results Safety How it works Questions

Which one is right for you?

Choose Cysteamine if…

Consider for diagnosed melasma when a suitable topical option is needed.

Diagnosed melasma
Hydroquinone isn’t suitable
You can follow short-contact wash-off

Choose Kojic Acid if…

Consider for uneven pigment if tolerated; evidence is mainly for combinations.

Mild uneven tone
Hydroquinone isn’t an option
You tolerate actives

Use care together

Can you use both?

Both can irritate. Use them at different times of day and add one at a time.

At a glance

● Cysteamine

● Kojic Acid

Type

Pigment-targeting active

Pigment-targeting ingredient

What it does

Can reduce melasma pigmentation in tested topical formulas.

May help uneven pigmentation, often as part of a combination treatment.

Best for

Melasma

Melasma

Studied concentrations

5% cream in controlled melasma trials; contact instructions vary by product.

2% added to hydroquinone and glycolic acid in the cited melasma study.

When to use

On the schedule specified for the product or prescribed treatment.

On the schedule specified for the product or prescribed treatment.

Time to results

Usually assessed over 8–16 weeks

Usually assessed over 8–16 weeks

Irritation

Odour, stinging and irritation may limit use; follow wash-off instructions.

Can cause stinging, redness or contact dermatitis.

Sensitive skin

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Available

Prescription or cosmetic status depends on the active, formula and country; check the label.

Prescription or cosmetic status depends on the active, formula and country; check the label.

What it helps

Compare uses by strength of evidence. Evidence level describes confidence in a benefit, not its size.

Evidence level

Cysteamine

Kojic Acid

Moderate evidenceSome supportive research

Flat tan patches with soft irregular edges across the forehead and upper cheek of an adult with light skin, the surface completely smooth.

Melasma

A placebo-controlled trial found reduced pigmentation with 5% cream.

—

Limited evidenceEarly or small studies

—

Flat tan patches with soft irregular edges across the forehead and upper cheek of an adult with light skin, the surface completely smooth.

Melasma

Adding 2% kojic acid improved results in a small combination-treatment trial.

Insufficient evidence

Flat light-brown residual marks on a fair cheek.

Post-Inflammatory Hyperpigmentation

The cited melasma trial does not establish fading of every type of dark mark.

The front of a forearm on fair skin. Two pale patches with sharp edges sit against lightly tanned skin, and the difference between the patch and the skin around it is subtle.

Vitiligo

The reviewed sources do not establish this ingredient as a treatment for this concern.

Sensitive Skin on light skin.

Sensitive Skin

The reviewed sources do not establish this ingredient as a treatment for this concern.

Flat light-brown residual marks on a fair cheek.

Post-Inflammatory Hyperpigmentation

The cited melasma trial does not establish an independent effect on post-acne marks.

The front of a forearm on fair skin. Two pale patches with sharp edges sit against lightly tanned skin, and the difference between the patch and the skin around it is subtle.

Vitiligo

The reviewed sources do not establish this ingredient as a treatment for this concern.

Sensitive Skin on light skin.

Sensitive Skin

The reviewed sources do not establish this ingredient as a treatment for this concern.

AI-generated educational illustration of Sun Spots: 1. Sun Spots Header — Light Skin; Lighter skin. Not a clinical photograph.

Sun Spots

The reviewed sources do not establish this ingredient as a treatment for this concern.

How it works

Cysteamine mechanism diagram. Affects melanin formation: Cysteamine acts through several pigment pathways. May help melasma: The formula, contact time and tolerance matter. — Open full-size diagram
Diagram explanation and sources
Affects melanin formation: Cysteamine acts through several pigment pathways. May help melasma: The formula, contact time and tolerance matter.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.
Source 1

Kojic Acid mechanism diagram. Reduces tyrosinase activity: Kojic acid interferes with melanin production. Less new pigment forms: Effects depend on the formula and tolerance. — Open full-size diagram
Diagram explanation and sources
Reduces tyrosinase activity: Kojic acid interferes with melanin production. Less new pigment forms: Effects depend on the formula and tolerance.
Schematic illustration; not a measurement of skin penetration. Effects vary with ingredient identity and formulation.
Source 1

Using both in one routine

Built from where each one usually sits in a routine. Introduce one at a time.

Morning

Step 1

Cleanser

Step 2

Moisturizer

Step 3

Sunscreen

Night

Step 1

Cleanser

Step 2

Kojic AcidNight

Step 3

CysteamineNight

Step 4

Moisturizer

Strengths and forms

Concentrations

5% cysteamine cream is the main concentration studied for melasma. Contact time is product-specific; some studied formulas are short-contact treatments rather than overnight creams.

5%

Studied melasma cream

Controlled trials studied this strength. One short-contact trial used a specific cream; follow the current product’s instructions rather than copying a study schedule.

Choosing a strength: Choose a finished topical product with clear instructions for how long to leave it on and when to rinse.

Higher strengths: There is no established benefit from escalating beyond the studied strength. Burning, redness or a persistent rash are reasons to stop and reassess.

Formula matters: Stabilization, the base cream and exposure time affect tolerability. Different cysteamine formulations need not have identical instructions.

Kojic acid concentrations in older studies differ from current cosmetic limits. In the EU, kojic acid is limited to 1% in face and hand products; that is not a universal treatment target.

1%

2%

EU cosmetic ceiling

The maximum in specified face and hand products. This is a regulatory limit, not proof of the best efficacy.

Older combination-study strength

Studied with hydroquinone and glycolic acid. The combination result does not isolate kojic acid or establish a current home-use recommendation.

Choosing a strength: Check local rules and the full formula. Kojic acid and kojic dipalmitate are different ingredients and cannot be compared by percentage alone.

Higher strengths: Do not use an older trial’s concentration as a reason to exceed current limits. Irritation or allergic contact dermatitis can occur.

Formula matters: Combination products may obtain benefit from several ingredients. A study of a combination cannot tell you what kojic acid alone contributed.

Forms

Cream

Serum · Soap · Cream

When you’ll see results

Approximate windows, not promises.

● Cysteamine

● Kojic Acid

First few weeks

First few weeksAssess tolerance first; pigment change is usually slower.

First few weeksAssess tolerance first; pigment change is usually slower.

4–8 weeks

4–8 weeksSome studied regimens begin showing pigment improvement.

4–8 weeksSome studied regimens begin showing pigment improvement.

8–12 weeks

8–12 weeksA useful review point for benefit and irritation.

8–12 weeksA useful review point for benefit and irritation.

3–6 months

3–6 monthsMany melasma trials assess results over three to four months; recurrence is common.

3–6 monthsMany melasma trials assess results over three to four months; recurrence is common.

6–12 months

6–12 monthsLong-term use depends on the active; follow a monitored plan rather than extending treatment automatically.

6–12 monthsLong-term use depends on the active; follow a monitored plan rather than extending treatment automatically.

Safety and sensitive skin

Common reactions

Odour, stinging and irritation may limit use; follow wash-off instructions.

Can cause stinging, redness or contact dermatitis.

When to stop

Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.

Stop for persistent burning, swelling, blistering or a new rash. Seek urgent care for breathing difficulty or a severe allergic reaction.

Sensitive or inflamed skin

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Choose a simple formula and test a small area first. Avoid actively inflamed or broken skin unless the product is specifically directed for it.

Important limits

Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.

Do not use a cosmetic product as a substitute for diagnosis of an unexplained, changing or persistent skin problem.

Pregnancy

Data in pregnancy are limited; ask the clinician managing your pregnancy before using.

There is not much pregnancy-specific data on kojic acid, and melasma often appears or worsens in pregnancy. Ask the doctor managing your pregnancy first. Azelaic acid and strict sun protection are the usual alternatives.

How it works

In the skin

On the skin. The finished product delivers cysteamine in a particular vehicle.

Entering skin. Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.

Conversion. No activation step is established as necessary for its intended topical role.

Skin response. Acts on pigment-related pathways; the cream, contact time and tolerance influence its practical effect.

Additional effects. Proposed pathways do not establish a measured depth of delivery or clinical benefit beyond the studies cited.

On the skin. The finished product delivers kojic acid in a particular vehicle.

Entering skin. Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.

Conversion. No activation step is established as necessary for its intended topical role.

Skin response. Inhibits tyrosinase activity involved in melanin production; cosmetic formulas differ from studied combinations.

Additional effects. Proposed pathways do not establish a measured depth of delivery or clinical benefit beyond the studies cited.

Getting in

Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.

Below the 500 Da guideline; delivery still depends on the formula, solubility, stability and skin condition. Size does not prove effectiveness or penetration depth.

Molecule size

Cysteamine · 77 Da

Kojic Acid · 142 Da

Smaller than 500 Da passes the outer skin more easily. Size isn’t an effectiveness score.

500 Da guideline

Common questions

Cysteamine:What should I choose cysteamine for?

Consider for diagnosed melasma when a suitable topical option is needed.

Cysteamine:How strong is the evidence?

A small placebo-controlled study supports 5% cream over four months. Active-comparator studies are small and do not prove equal efficacy to hydroquinone. The mass shown refers to the free base, not its hydrochloride salt.

Kojic Acid:What should I choose kojic acid for?

Consider for uneven pigment if tolerated; evidence is mainly for combinations.

Kojic Acid:How strong is the evidence?

A 40-woman split-face trial added kojic acid to hydroquinone and glycolic acid. It does not show that kojic acid alone performs as well as the combination or that higher strengths are better.

Sources

Sources and further reading

Dermapedia on YouTube